Injection stretch blow molding method with upright preform molding and inverted blow molding

ABSTRACT

In an injection stretch blow molding method, at least one injection molded preform is transferred from a preform molding section to a blow molding section by way of a transfer section and the at least one preform is blow molded into at least one container in the blow molding section. In the preform molding section the at least one preform is injection molded in an upright state with an open neck section thereof facing upward. In the transfer section, the at least one upright preform is turned upside-down and transferred to the blow molding section in an inverted state. Then, the blow molding section blow molds at least one container from the at least one inverted preform.

BACKGROUND OF THE INVENTION

[0001] This invention relates to an injection stretch blow moldingapparatus and method wherein containers are stretch blow molded frompreforms retaining heat from when they were injection molded. Thisinvention also relates to an injection stretch blow molding apparatusand method wherein N (N>2) preforms are simultaneously injection moldedand n (1≦n<N) preforms among these are simultaneously blow molded into ncontainers. More particularly, the invention relates to an injectionstretch blow molding apparatus and method with which while ample coolingtime is provided the preforms can be molded with a shortened injectionmolding cycle time and furthermore the operation rate of the blowcavities can be increased. Also, this invention relates to constructionsand methods for heating and adjusting the temperature of the preformsbefore they are blow molded. Also, this invention relates to aninjection stretch blow molding apparatus and method with which it ispossible when necessary to discharge the preforms to outside theapparatus instead of carrying them to the blow molding section.

[0002] Methods for blow molding a container from a preform (parison)include that known as the cold parison or 2-stage method and that whichis known as the hot parison or 1-stage method. In both these methods,for injection molding the preforms required for the blow molding, atleast an injection cavity mold which shapes the outer wall of thepreform and an injection core mold which shapes the inner wall of thepreform are necessary. Also, after the injection cavity mold and theinjection core mold are clamped together and the preform is injectionmolded, with the molds still clamped together it is necessary to coolthe preform down to a temperature at which the preform can be releasedfrom the molds.

[0003] Particularly in the case of the cold parison (2-stage) method,because this preform mold-release temperature has to be made quite low,the injection molding cycle time has been long and productivity has beenpoor. This is because when the preform is ejected by the injectioncavity mold and the injection core mold being released from the preformand the preform being dropped or the like, it is necessary for thepreform to be cooled to a mold-release temperature low enough for thepreform not to be deformed when it makes contact with other members.

[0004] In the case of the cold parison method, because the preformmolding step and the step in which a container is blow molded from thispreform are completely release, the blow molding cycle time is notaffected by the injection molding cycle time. However, because the coldparison method involves reheating preforms which have been cooled toroom temperature the cold parison method is inferior to the hot parisonmethod in its energy efficiency.

[0005] In a hot parison (1-stage) method injection stretch blow moldingmachine which draw blow molds bottles from preforms still containingheat from when they were injection molded the cycle time of the overallapparatus is determined by the injection molding cycle time, which ofall the cycles is the one requiring the most time. Consequently therehas been the problem that when the time required for injection moldingis long, the throughput of the whole apparatus is low.

[0006] In the case of the hot parison method, although the preform ismold-released at a higher temperature than in the cold parison method,there is a limit on this mold-release temperature and consequently it isnot possible to greatly speed up the injection molding cycle. One reasonfor this is that when the preform mold-release temperature is high, whenthe injection core mold is released from the preform, a mold-releasecalled lifting, wherein the preform sticks to the core mold, occurs.Also, after the injection core mold is released from the preform,because there is no longer any member restricting deformation of thepreform, deformation caused by temperature nonuniformity and thermalcontraction and the like make it impossible for preforms conforming tothe design to be ejected. Furthermore, when the cooling effected by theinjection core mold is inadequate, crystallization caused by inadequatecooling occurs, particularly at the inner wall of the preform, and apreform of which the trunk portion is opaque is ejected.

[0007] Also, when preforms are ejected before they are completely cooledby the injection core mold and the injection cavity mold (with thepreforms still at a temperature at which blow molding is possible) andblow molding is carried out thereafter, there have been the followingproblems:

[0008] (A) Unless the internal pressure (injection sustain pressure) israised, shrink marks form at the injection cavity mold side of thepreform and a preform with a uniform temperature distribution cannot beobtained. Consequently, when this preform is blow molded, a moldedproduct with a uniform wall thickness distribution cannot be obtained.

[0009] (B) When the internal pressure (injection sustain pressure) israised, a pressure differential forms between the gate portion and thepreform end portion (for example the neck portion), and the resultingpreform has large residual stresses at the preform bottom end where thepressure was high. Consequently, when the preform is blow molded, amolded product with a uniform wall thickness distribution cannot beobtained.

[0010] (C) When the preform is cooled by the injection core mold and theinjection cavity mold, as the cooling progresses the preform contractsand tends to move away from the injection cavity surface. Because ofthis, there are some parts of the outer wall surface of the preformwhich are in contact with the injection cavity and some parts which arenot in contact with the injection cavity, and consequently differentparts of the preform cool at different rates and the temperature becomesuneven. As a result, when this preform is blow molded, a molded productof uniform wall thickness cannot be obtained.

[0011] Thus, in a conventional hot parison system, unless the preform isamply cooled by the injection cavity mold and the injection core mold ithas not been possible to obtain good blowing characteristics or goodbottle characteristics. Because of this, the injection molding of thepreforms has required time, and the throughput of the apparatus has beenlow.

[0012] Various other problems have also been associated with injectionstretch blow molding machines using the hot parison method, includingthe following:

[0013] When in order to increase the throughput the number N of preformsinjection molded simultaneously is increased, the same number N ofcavities conforming to the external shape of the bottles beingmanufactured have to be formed in the blow cavity mold. Of the moldsused in a blow molding machine the blow cavity mold is the mostexpensive, and the cost of this blow cavity mold increases roughly inproportion to the number of cavities in it. Even if a mold is expensive,if its operation rate is high then it can be used cost-effectively;however, because as described above the cycle time of the overallapparatus depends on the injection molding cycle time and cannot beshortened, the operation rate of each cavity in the blow cavity mold hasunavoidably been low. Also, when the number of bottles blow moldedsimultaneously increases, not only the number of cavities in the blowmold but also the number of drawing rods and blow core molds andmechanisms for supporting and driving these increases, and this hasresulted in increases in the size and cost of the apparatus.

[0014] Another problem has been that conventionally it has not beenpossible to eject the preforms unless the injection core mold iscompletely pulled out of the preforms, and consequently with a rotaryinjection molding apparatus it has not been possible to carry thepreforms from the injection molding section to the next stage. When onthe other hand the injection core mold is completely pulled out of thepreforms, there has been the problem that this pullout stroke is longand the overall height of the apparatus is high.

[0015] Another problem has been that when hot parison blow molding iscarried out by a rotary carrier type blow molding machine the injectionmolded preforms are always carried by the rotary carrier to the blowmolding section. Here, for example when a problem has arisen in the blowmolding section, there has been no alternative but to shut down thepreform injection molding as well as the blow molding section. However,once the injection molding section is shut down, a long starting-up timeis required when it is restarted. This is because the injectionapparatus contains numerous resin-heating mechanisms in the hot runnermold and elsewhere.

[0016] As a result, as well as it not being possible to raise thethroughput of the overall apparatus, as described above, a lot of timeis required for starting up the apparatus when a problem has arisen, andthe productivity falls even further.

[0017] Accordingly, it is an object of the invention to provide aninjection stretch blow molding apparatus and method with which whileample preform cooling time is provided the injection molding cycle timecan be shortened and the cycle time of the overall apparatus can therebybe shortened.

[0018] Another object of the invention is to provide a highly efficientinjection stretch blow molding apparatus and method with which whilereducing costs by reducing the number of cavities in the blow mold theoperation rate of the blow mold can be increased.

[0019] Another object of the invention is to provide an injectionstretch blow molding apparatus and method which while exploiting theheat energy efficiency of hot parison molding also has the preformtemperature distribution stability of the cold parison method.

[0020] Another object of the invention is to provide an injectionstretch blow molding apparatus and method with which temperaturenonuniformity and deformation can be prevented even when the preformmold-release temperature at which the preforms are released from theinjection cavity mold is made high and furthermore the preforms can beamply cooled before they are released from the injection core mold andcan be stably blow molded thereafter at a suitable blow moldingtemperature.

[0021] A further object of the invention is to provide an injectionstretch blow molding apparatus and method with which the temperaturedifference between the inner and outer walls of the preforms ismoderated before the preforms are blow molded.

[0022] A further object of the invention is to provide an injectionstretch blow molding apparatus with which general-purpose medium-sizedcontainers of capacity 1 to 3 liters can be blow molded with highefficiency.

[0023] A further object of the invention is to provide a blow moldingapparatus with which it is possible to efficiently heat the regionsbelow the necks of the preforms to a suitable blow molding temperature.

[0024] A further object of the invention is to provide a blow moldingapparatus with which it is possible to moderate the temperaturedifference between the inner and outer walls of the preforms and alsouse this time provided for temperature moderation to adjust thetemperature of the preforms to a suitable blow molding temperaturebefore blow molding is carried out.

[0025] A further object of the invention is to provide an injectionstretch blow molding apparatus and method which can be started upwithout any wasteful blow molding being carried out at the time ofstart-up and with which it is not necessary to stop the operation of thewhole apparatus when there is a problem in the blow molding section.

[0026] An injection stretch blow molding apparatus according to theinvention comprises:

[0027] a preform molding station for injection molding preforms;

[0028] a blow molding station for stretch blow molding the preforms intocontainers; and

[0029] a transfer station for transferring the preforms from the preformmolding station to the blow molding station,

[0030] wherein the preform molding station comprises:

[0031] a circulatory carrier for intermittently circulatorily carryingalong a carrying path a plurality of injection core molds disposedapart;

[0032] an injection molding section for injection molding the preformshaving an injection cavity mold together with which the injection coremolds, stopped in the carrying path, are severally clamped; and

[0033] an ejecting section for ejecting preforms from the injection coremolds by releasing the injection core molds, stopped in the carryingpath, and the preforms.

[0034] An injection stretch blow molding method according to theinvention for blow molding containers from preforms retaining heat fromwhen the preforms were injection molded comprises the steps of:

[0035] releasing the preforms, molded using at least an injection coremold and an injection cavity mold, from the injection cavity mold;

[0036] with the preforms held by the injection core mold, carrying theinjection core mold to an ejecting section along a carrying path whilethe preforms are cooled by the injection core mold;

[0037] in the ejecting section, ejecting the preforms by releasing theinjection core mold therefrom; and

[0038] thereafter, blow molding the containers from the preformsretaining heat from when the preforms were injection molded.

[0039] According to these inventions, the preforms injection molded inthe injection molding section are cooled by the injection cavity moldand the injection core mold and then the injection cavity mold only isreleased from the preforms. After that, the preforms are carried to thepreform ejecting section by the injection core mold. The preforms areejected after being cooled by the injection core mold during thiscarrying and in the preform ejecting section. As a result, by thepreforms being cooled by the injection core mold even after theinjection cavity mold is mold-released in the injection molding section,ample preform cooling time is provided. Therefore, the preformmold-release temperature at which the preforms are released from theinjection cavity mold can be made high, the injection molding cycle timecan thereby be shortened and the cycle time of the overall apparatus canbe shortened. Also, even when the preforms are released from theinjection cavity mold at a high temperature, deformation of the preformsis prevented by the injection core mold. Furthermore, not only does thecooling efficiency increase because the preforms contract into contactwith the injection core mold as they are cooled, and consequentlycrystallization and loss of transparency of the trunk portions of thepreforms caused by inadequate cooling is prevented, but also by thusstabilizing the cooling process it is possible to stabilize the amountof heat retained by the preforms and thereby stabilize the wallthickness distributions of successively blow molded containers.

[0040] According to another aspect of the invention, an injectionstretch blow molding apparatus comprises:

[0041] a preform molding station for injection molding preforms;

[0042] a blow molding station for stretch blow molding the preforms intocontainers; and

[0043] a transfer station for transferring the preforms from the preformmolding station to the blow molding station,

[0044] wherein the preform molding station comprises:

[0045] a first circulatory carrier for intermittently circulatorilycarrying along a first carrying path an injection core mold having N(N>2) of core pins disposed apart;

[0046] an injection molding section for simultaneously injection moldingN of the preforms, said injection molding section having an injectioncavity mold including N of cavities in which the injection cavity moldis clamped together with the injection core mold stopped in the firstcarrying path; and

[0047] an ejecting section for ejecting preforms from the injection coremold by releasing from the injection core mold, stopped in the firstcarrying path,

[0048] and the blow molding station comprises:

[0049] a second circulatory carrier for intermittently circulatorilycarrying along a second carrying path the preforms transferred from thepreform molding station by the transfer station; and

[0050] a blow molding section for simultaneously blow molding n (1≦n<N)of containers from n of the preforms, said blow molding section having ablow mold including n of blow cavities in which the blow mold is clampedaround the preforms stopped in the second carrying path.

[0051] According to another aspect of the invention, an injectionstretch blow molding method for molding containers from preformsretaining heat from when the preforms were injection molded, comprisingthe steps of:

[0052] releasing N (N>2) of the preforms, molded using at least aninjection core mold and an injection cavity mold, from the injectioncavity mold;

[0053] with the preforms held by the injection core mold, carrying theinjection core mold to an ejecting section along a first circulatorycarrying path while the preforms are cooled by the injection core mold;

[0054] in the ejecting section, ejecting the preforms by releasing fromthe injection core mold;

[0055] transferring the ejected preforms to carrier members to becarried along a second circulatory carrying path;

[0056] carrying the carrier members supporting the preforms along thesecond carrying path to a blow molding section; and

[0057] in the blow molding section, simultaneously blow molding n(1≦n<N) of containers from n of the preforms in a blow mold clampedaround n of the preforms.

[0058] According to these inventions, the inventions provide thefollowing operations and effects in addition to those of the inventionsas described above: Because the number n of preforms simultaneously blowmolded is made smaller than the number N of preforms simultaneouslyinjection molded, fewer cavities are required in the blow mold and moldcosts, molds being consumable items, can be greatly reduced. Also,because fewer blow core molds, stretching rods, and mechanisms forsupporting and driving these are required, the apparatus can be mademore compact and cheaper. Furthermore, because N simultaneously moldedpreforms are blow molded n (n<N) at a time over a plurality of blowmolding cycles within the shortened injection molding cycle time, theoperating rate of the n cavities in the blow cavity mold increases.

[0059] Here, a heating section for heating the preforms being carried tothe blow molding section can be provided. When this is done, thepreforms can be brought to a temperature suitable for blow molding bycooling performed by the injection molds and reheating of the cooledpreforms, and the temperature stability from cycle to cycle thereforeincreases. Also, even though N simultaneously injection molded preformsare blow molded n preforms at a time over (N/n) blow molding cycles,control reducing the temperature variation among blow molding cycles caneasily be carried out.

[0060] Also, when the preforms being heated are rotated about theirvertical center axes, heating unevenness is reduced and temperaturenonuniformity in the circumferential direction of the preforms canthereby be reduced.

[0061] Furthermore, a second circulatory carrier comprises a pluralityof carrier members which remain spaced at equal intervals along thesecond carrying path, and each of the carrier members has a supportingportion for supporting a preform in an inverted or an upright state. Itis preferable that the array pitch at which the plurality of carriermembers are spaced along the second carrier path be made equal to thearray pitch P of the plurality of cavities in the blow cavity mold. Thisis because it makes pitch conversion in the carrying processunnecessary. When this is done, the array pitch of the preforms in theheating section of the invention is greater than the small pitch atwhich the preforms are arrayed in the heating section in a conventional2-stage system. However, because in this invention it is only necessaryto give the preforms a small amount of heat energy in addition to theheat which they retain from when they were injection molded, the heatingtime can be short and the length of the heating section does not have tobe made long as it does in the cold parison case.

[0062] Also, in the method of this invention, a step of allowing thepreforms to cool between the separation of the preforms from theinjection core mold and the start of the blow molding step, over aperiod of time long enough for the temperature difference between theinner and outer walls of the preforms to be moderated, can be provided.Here, when the method of this invention is applied, because the periodof time for which the preforms are cooled by the injection core mold incontact with their inner walls is made longer than conventionally, arelatively steep temperature gradient forms between the inner and outerwalls of the preforms, and the temperature in the outer wall vicinitybecomes greater than that in the inner wall vicinity. By providing thiscooling step, this temperature gradient can be moderated and the innerand outer walls of the preforms can be brought to a temperature suitablefor blow molding.

[0063] Also, in the method of this invention, it is preferable that inthe blow molding step n (n≧2) containers simultaneously be blow moldedfrom n preforms using n blow cavities arrayed at a blow molding pitch P,that the preforms being carried along the second carrying path becarried with the array pitch of the carrier members kept equal to thispitch P, and that in the preform transferring step a process wherein npreforms are simultaneously transferred to n carrier members is repeateda plurality of times.

[0064] When this is done, as well as no carrying pitch conversion in thesecond carrying path being necessary, even if the number of preformssimultaneously injection molded N is increased, because only n preformsare transferred at a time, fewer than when N preforms are simultaneouslytransferred, the preforms can be easily correctly positioned on thecarrier members, and also no complex mechanisms are required to do this.

[0065] According to another aspect of the invention, an injectionstretch blow molding method wherein injection molded preforms aretransferred from a preform molding station to a blow molding station byway of a transfer station and the preforms are blow molded intocontainers in the blow molding station is characterized in that:

[0066] in the preform molding station the preforms are injection moldedin an upright state with open neck portions thereof facing upward;

[0067] the transfer station turns the upright preforms upside-down andtransfers the preforms to the blow molding station in an inverted state;and

[0068] the blow molding station blow molds containers from the invertedpreforms.

[0069] According to the invention, the preforms are molded in an uprightstate with their neck portions facing upward. As a result, the injectionmold clamping is vertical clamping and is therefore space-saving. Also,because resin is normally injected from the preform bottom portion side,a stable arrangement wherein the injecting apparatus and the injectioncavity mold are disposed on a machine bed and the injection core mold isdisposed thereabove can be employed. Also, because when the preforms arecarried to the blow molding station they are in an inverted state, theopenings at their neck portions can be used to have the preforms supportthemselves easily. Furthermore, because the drawing rods and blow coremolds consequently have to be positioned underneath the preforms, theycan be disposed using a space in the machine bed and the overall heightof the blow molding section can be made low.

[0070] According to another aspect of the invention, an injectionstretch blow molding method comprises the steps of:

[0071] simultaneously injection molding N of preforms made ofpolyethylene terephthalate using at least an injection core mold and aninjection cavity mold;

[0072] releasing the preforms from the injection cavity mold;

[0073] carrying the preforms to an ejecting section while cooling thepreforms by means of the injection core mold;

[0074] in the ejecting section, after the preforms have been cooled to apredetermined temperature, ejecting the preforms from the injection coremold;

[0075] heating the ejected preforms to a predetermined temperature; and

[0076] thereafter, simultaneously blow molding n of containers from n ofthe preforms,

[0077] wherein the ratio of the numbers N and n is N:n=3:1.

[0078] According to experiments carried out by the present inventors, inthe case of a general-purpose medium-sized container of capacity 1 to 3liters having a relatively small mouth (the diameter of the opening inthe neck portion 2 being about 28 to 38 mm) for which the market demandis large, the ratio of the simultaneous molding numbers N, n shouldideally be set to N:n=3:1. That is, it has been found that in the caseof this invention wherein the preforms continue to be cooled by theinjection core mold even after the preforms are removed from theinjection cavity mold and then blow molded thereafter, the time requiredfor the injection molding of a preform for a general-purposemedium-sized container is shortened to approximately ¾ of that in thecase of a conventional injection stretch blow molding apparatus, and aninjection molding cycle time of approximately 10 to 15 seconds issufficient. A blow molding cycle time, on the other hand, of 3.6 to 4.0seconds is sufficient. Therefore, if this injection molding cycle timeis T1 and the blow molding cycle time is T2, the ratio T1:T2 is roughly3:1, and to mold general-purpose medium-sized containers efficiently thesimultaneous molding numbers N, n should ideally be set according tothis ratio.

[0079] According to another aspect of the invention, an injectionstretch blow molding method comprises the steps of:

[0080] simultaneously injection molding N (N>2) of preforms; and

[0081] simultaneously blow molding n (1≦n<N) of containers from n of thepreforms retaining heat from when the preforms were injection molded,

[0082] wherein N/n is an integer when the injection and blow moldingsteps are repeated.

[0083] When N/n is an integer, for example the N preforms simultaneouslyinjection molded in a first cycle are all used over an integral number(N/n) of blow molding cycles n at a time, and none of these preforms aremixed with and simultaneously blow molded with any of the N preformssimultaneously molded in the subsequent second cycle. If preforms fromdifferent injection molding cycles are mixed and blow molded together,the carrying sequence is different from the case wherein preforms moldedin the same injection molding cycle are simultaneously blow moldedtogether, and the control and structure of the apparatus becomecomplicated; however, this invention eliminates this problem.

[0084] According to another aspect of the invention, a blow moldingapparatus wherein preforms carried in an inverted state with neckportions thereof facing downward or in an upright state with the neckportions facing upward are heated in a heating section before beingcarried to a blow molding section is characterized in that:

[0085] the heating section comprises:

[0086] a plurality of first heaters disposed at one side of a preformcarrying path, spaced apart in a vertical direction and extending in apreform carrying direction;

[0087] a reflecting plate disposed facing the first heaters across thepreform carrying path; and

[0088] a plurality of second heaters extending in the preform carryingdirection on both sides of the preform carrying path,

[0089] wherein the second heaters are positioned at such a height in thevertical direction that they face regions subject to blow molding in thevicinities of the neck portions of the preforms.

[0090] According to the invention, although the region below the neckportion when the preform is upright is the nearest to the cavity surfaceof the blow cavity mold, it is a region which is to be draw orientatedrelatively much. By heating this region with the second heaters oneither side of the preform, it can be heated to a higher temperaturethan the trunk portion region heated by the first heaters disposed onone side only, and a high drawing orientation degree can be secured.Also, because the first heaters are disposed on one side only, thearrangement is saving. Furthermore, because the efficiency with whichthe region below the neck is heated increases, there is the benefit thatthe heating time can be shortened and the overall length of the heatingsection can be made short.

[0091] According to another aspect of the invention, a blow moldingapparatus comprises:

[0092] carrier members which support and intermittently circulatorilycarry preforms;

[0093] a heating section having heaters extending in a preform carryingdirection;

[0094] an endless carrying member running along the preform carryingdirection at least through a heating zone of the heating section; and

[0095] a driver for driving the endless carrying member in a forwarddirection,

[0096] wherein each of the carrier members has a rotary driven memberfor meshing with the endless carrying member and a preform supportingportion which rotates integrally with the rotary driven member, and

[0097] the forward direction of the endless carrying member where itmeshes with the rotary driven members is opposite to the preformcarrying direction.

[0098] According to the invention, while the preforms are stopped thepreforms are rotated in one direction by the meshing of the endlesscarrying member moving forward in a fixed direction and the rotarydriven member rotated in a fixed position, and temperature nonuniformityof the preforms can thereby be prevented. Also, when the preforms aremoving, because the endless carrying member moves forward in theopposite direction to that in which the preforms are being carried, thepreforms are rotated faster in the same direction and temperaturenonuniformity is similarly prevented. If the endless carrying memberwere to move forward along with the preforms in the same direction asthe rotary driven member, because the preforms would only be rotated bythe speed differential between the endless carrying member and therotary driven member, the preforms would rotate slowly or not at all.Also, there would be cases wherein the direction of the rotation of thepreforms was different from that as of when the preforms were stopped.All these situations would cause temperature nonuniformity in thepreforms; however, according to the invention, this temperaturenonuniformity is eliminated.

[0099] According to another aspect of the invention, a blow moldingapparatus wherein preforms are intermittently carried to a blow moldingsection via a heating section is characterized in that:

[0100] the heating section comprises a heater extending in a preformcarrying direction at one side of a preform carrying path, and

[0101] in the carrying path between the heating section and the blowmolding section a standby section is provided where at least enoughnumber of preforms for one blow molding cycle are stopped and made tostandby before being carried into the blow molding section.

[0102] According to the invention as set forth in claim 20, by a standbysection being provided before the blow molding section, the temperaturedistributions in the synthetic resin preforms, which have poor thermalconductivity, can be moderated. Normally, because heating in the heatingsection is carried out from around the preforms, the inner walltemperature of the preforms becomes lower than the outer walltemperature. By having at least the number of preforms simultaneouslyblow molded standby after being heated in order to moderate theresulting temperature gradients therein, the blow moldingcharacteristics are stabilized.

[0103] Also, by actively carrying out temperature adjustment on thepreforms during this temperature moderation time in the standby section,the preforms can be given a temperature distribution for blow moldingwhich could not be obtained just by simply heating the preforms whilerotating them.

[0104] According to another aspect of the invention, an injectionstretch blow molding apparatus comprising a preform molding section formolding preforms and a blow molding section for blow molding containersfrom the preforms retaining heat from when the preforms were injectionmolded is characterized in that:

[0105] at a location in a path along which the preforms are carried fromthe preform molding section to the blow molding section there isprovided a discharge guide section for guiding preforms which are not tobe carried to the blow molding section off the carrying path.

[0106] According to another aspect of the invention, an injectionstretch blow molding method wherein preforms are injection molded in apreform molding section and these preforms are carried to a blow moldingsection and containers are blow molded from the preforms retaining heatfrom when the preforms were injection molded comprises the steps of:

[0107] switching to either a container molding operating mode or apreform molding operating mode; and

[0108] when the preform molding operating mode is switched to, part wayalong the preform carrying path leading to the blow molding section,discharging the preforms being molded in the preform molding section tooff the carrying path.

[0109] According to these inventions, because it is possible todischarge imperfect preforms molded during molding start-up instead ofcarrying them to the blow molding section, wasteful blow molding can beavoided. Also, when a problem arises in the blow molding section or whenadjustments have to be made thereto, repair or adjustment of the blowmolding section is possible without stopping the operation of thepreform molding station. Once the preform molding station is shut down,it takes a long time to restore the various heating mechanisms to astate wherein molding is possible; however, with this invention thiskind of wasteful starting up time is eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS

[0110]FIG. 1 is a plan view of a preferred embodiment of the invention;

[0111]FIG. 2 is a front view of the preferred embodiment apparatus shownin FIG. 1;

[0112]FIG. 3 is a left side view of the preferred embodiment apparatusshown in FIG. 1;

[0113]FIG. 4 is an enlarged view of the main parts of the apparatusshown in FIG. 1;

[0114]FIG. 5 is an underside view of a rotary disc;

[0115]FIG. 6 is a perspective view showing the mold-released state of aninjection core mold when a neck presser plate has been lowered;

[0116]FIG. 7 is a partially sectional view showing the injection coremold and a neck cavity mold mounted on the rotary disc;

[0117]FIG. 8 is a view illustrating a preform ejecting drive mechanism;

[0118]FIG. 9 is an enlarged sectional view of portion A in FIG. 8;

[0119]FIG. 10 is a partially sectional view illustrating themold-released state of the injection core mold;

[0120]FIG. 11 is a partially sectional view illustrating a preform 1ejecting operation;

[0121]FIG. 12 is a view illustrating the operation of a transfer stationreceiving a preform;

[0122]FIG. 13 is a view illustrating the operation of a transfer stationhanding a preform over to a blow molding station;

[0123]FIG. 14 is a plan view of the transfer station;

[0124]FIG. 15 is a side view of the transfer station;

[0125]FIG. 16 is a plan view of a carrier member of a second circulatorycarrier provided in the blow molding station;

[0126]FIG. 17 is a side view of the carrier member shown in FIG. 16;

[0127]FIG. 18 is a partially cut-away front view of the carrier membershown in FIG. 16;

[0128]FIG. 19 is a side view in the preform carrying direction of aheating section;

[0129]FIG. 20 is a plan view showing in outline a rotating carriermechanism of the heating section;

[0130]FIG. 21 is a plan view showing another preferred embodimentapparatus of the invention wherein the numbers of preforms moldedsimultaneously are different from those of the apparatus of FIG. 1;

[0131]FIG. 22 is a view illustrating the operation of a transfer stationtransferring preforms while converting their pitch;

[0132]FIG. 23 is a sectional view of a temperature adjusting coredisposed in a standby section;

[0133]FIG. 24 is a sectional view of a temperature adjusting potdisposed in the standby section;

[0134]FIG. 25 is a sectional view of local temperature adjusting membersdisposed in the standby section; and

[0135]FIG. 26 is a view of a flat container blow molded after thetemperature adjusting shown in FIG. 25.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0136] A preferred embodiment wherein the method and apparatus of theinvention are applied will be described below with reference to theaccompanying drawings.

[0137] Overall Constitution of the Apparatus

[0138]FIG. 1, FIG. 2 and FIG. 3 respectively are a plan view, a frontview and a left side view of the apparatus of this preferred embodiment,and FIG. 4 is an enlarged view showing the main parts of the apparatusof the preferred embodiment. As shown in the drawings, the apparatuscomprises a preform molding station 10, a transfer station 200 and ablow molding station 300 disposed on a machine bed 8.

[0139] As shown in FIG. 2, the preform molding station 10 has a rotarydisc 30 which has an injection core mold 50 in each of two locations anangle of rotation 180° apart and is a first circulatory carrier whichcirculatorily carries the injection core molds 50 intermittently along arotary carrying path. An injection molding section 14 facing aninjecting apparatus 12 and a preform ejecting section 16 facing thisinjection molding section 14 are respectively provided at the stoppingpositions of the injection core molds 50. The injection molding section14 has an injection cavity mold 42 to which an injection core mold 50can be clamped, and with this injection cavity mold 42 the injectionmolding section 14 simultaneously injection molds N (N≧2), for exampleN=4, preforms 1 at a time. In the preform ejecting section 16, theinjection core mold 50 is released from the preforms 1. In thispreferred embodiment, a neck portion of each preform 1 is molded bymeans of a neck cavity mold 60 which will be further discussed later,and the preforms 1 are held by this neck cavity mold 60 and theinjection core mold 50 and carried by the rotary disc 30 to the preformejecting section 16. In the preform ejecting section 16 the preforms 1are ejected by being released from the neck cavity mold 60 after apartial release of the injection core mold 50.

[0140] As shown in FIG. 1, the blow molding station 300 has a secondcirculatory carrier 302 comprising four sprockets 320 a to 320 d and acarrier chain 322 running around these sprockets. A plurality of forexample ten carrier members 330 are fixed to this carrier chain 322uniformly spaced apart, and a preform 1 or a bottle 6 is supported byeach carrier member 330. In the carrying path of the carrier members 330are provided a preform receiving section 304 which receives the preforms1 from the transfer station 200, a heating section 306 which heats thepreforms 1, a standby section 308 which causes the heated preforms 1 totemporarily standby, a blow molding section 310 which blow molds thepreforms 1 into bottles 6, and a bottle ejecting section 312 whichejects the bottles 6 to outside the apparatus.

[0141] The blow molding section 310 has a blow mold 378 which is clampedaround the preforms 1 and blow molds one bottle 6 from each of n (1≦n<N)preforms 1, for example n=1 preform 1.

[0142] The transfer station 200 transfers the preforms 1 ejected fromthe preform ejecting section 16 of the preform molding station 10 to thepreform receiving section 304 of the blow molding station 300. In thepreform ejecting section 16 of the preform molding station 10 N preforms1, i.e. the number of preforms 1 simultaneously molded in the injectionmolding section 14, are ejected at a time, but in the transfer station200 n preforms 1, i.e. the number of preforms 1 simultaneously molded inthe blow molding section 310 of the blow molding station 300, aretransferred at a time. In the apparatus of this preferred embodiment,four preforms 1 simultaneously ejected by the preform ejecting section16 are transferred one at a time to the preform receiving section 304.Also, whereas in the preform molding station 10 the preforms 1 areinjection molded in an upright state, in the transfer station 200 thepreforms 1 are turned upside-down and transferred to the blow moldingstation 300 in an inverted state.

[0143] Preform Molding Station 10

[0144] First the preform molding station 10 will be described, withreference to FIG. 1 to FIG. 11.

[0145] Injection Molding Section 14 and First Circulatory Carrier 30

[0146] As shown in FIG. 2 and FIG. 4, the injection molding section 14of the preform molding station 10 is provided with a lower clampingplate 20 mounted on the machine bed 8. A for example circular upperclamping plate 22 is disposed above this lower mold clamping plate 20and extends from the injection molding section 14 into the preformejecting section 16. This upper mold clamping plate 22 is movablevertically along four tie bars 24 provided in four locations around theinjection molding section 14. As shown in FIG. 1, FIG. 2 and FIG. 4, afixed plate 26 is mounted on the upper ends of the tie bars 24 and aclamping cylinder 28 is mounted on this fixed plate 26. The clampingcylinder 28 drives a clamping rod 28 a (see FIG. 4), and the upperclamping plate 22 is driven up and down by this clamping rod 28 a.

[0147] As shown in FIG. 2 to FIG. 4, the rotary disc 30 constituting thefirst circulatory carrier is rotatably mounted at the underside of theupper clamping plate 22. As shown in FIG. 7, this rotary disc 30 isfixed to a rotational shaft 34 rotationally driven by a rotary actuator32 fixed to the upper clamping plate 22. As shown in FIG. 5, which is anunderside view of the rotary disc 30, the two injection core molds 50and the two neck cavity molds 60 are mounted on the rotary disc 30 inpositions corresponding to the injection molding section 14 and thepreform ejecting section 16. The details of the injection core molds 50and the neck cavity molds 60 will be discussed in detail later.

[0148] As shown in FIG. 2 and FIG. 4, the injection molding section 14is provided with a hot runner mold 40 with which a nozzle of theinjecting apparatus 12 nozzle-touches, and the injection cavity mold 42is mounted on this hot runner mold 40. This injection cavity mold 42 hasa cavity for each of the N preforms 1 simultaneously molded in theinjection molding section 14, for example four cavities. This injectioncavity mold 42 is capable of cooling the injection molded preforms, anda coolant, for example water at room temperature, is circulatedtherethrough.

[0149] As shown in FIG. 4 to FIG. 8, the two injection core molds 50mounted on the rotary disc 30 each have the same number of core pins 52as the number N of preforms simultaneously molded, for example four corepins 52. As shown in FIG. 7, the base portions 52 a of these core pins52 are supported by a core presser plate 54 fixed to the underside ofthe rotary disc 30 and a core fixing plate 56 fixed to the underside ofthis core presser plate 54. When the clamping cylinder 28 is driven andthe clamping rod 28 a drives down the upper clamping plate 22, the corepins 52 of the injection core mold 50 are driven down integrally withthe rotary disc 30, the core presser plate 54 and the core fixing plate56 mounted on this upper clamping plate 22 and are thereby clamped ontothe injection cavity mold 42.

[0150] As shown in FIG. 7 and FIG. 11, the two neck cavity molds 60mounted on the rotary disc 30 are made up of pairs of split molds 62 aand 62 b, each neck cavity mold 60 comprising the same number of pairsof split molds 62 a and 62 b as the number N of preforms simultaneouslymolded, for example four. The pairs of split molds 62 a and 62 b of eachneck cavity mold 60 are fixed by split plates 64 a and 64 b, and thesesplit plates 64 a and 64 b constitute a neck fixing plate 64. As shownin FIG. 11, a neck presser plate 65 which pushes this neck fixing plate64 downward is disposed on the upper surface side of the split plates 64a and 64 b. Also, there are provided guide plates 66 which support theundersides of the ends of the neck fixing plate 64. The split plates 64a and 64 b are kept normally closed by springs 64 c shown in FIG. 5. Asshown in FIG. 5, a wedge hole 64 d is provided at each end of the splitplates 64 a and 64 b. After the neck fixing plate 64 has been carriedinto the preform ejecting section 16, the split plates 64 a and 64 b areopened by being driven apart along the guide plates 66 by split plateopening cams 108, which will be further discussed later, driven into thewedge holes 64 d.

[0151] As shown in FIG. 9, which is an enlarged sectional view ofportion A of FIG. 8, and in FIG. 6, at each end of each guide plate 66 avertical lifting and lowering pin 70 has its lower end fixed in theguide plate 66, and a flange 70 a is formed at the upper end of thislifting and lowering pin 70. A guide cylinder 72 extends downward fromthe underside of the rotary disc 30, and the lifting and lowering pin 70is disposed inside this guide cylinder 72. A return spring 74 isdisposed between the inner wall of the bottom portion of the guidecylinder 72 and the flange 70 a of the lifting and lowering pin 70. Theupward urging force of these return springs 74 urges the guide plate 66upward at all times, and as a result the neck presser plate 65 isnormally in contact with the underside of the core fixing plate 56.

[0152] By this state of contact between the core fixing plate 56 and theneck presser plate 65 being maintained, the injection core mold 50 andthe neck cavity mold 60 are kept clamped together. When in the preformejecting section 16 an external force (which will be further discussedlater) is applied to the lifting and lowering pins 70, the lifting andlowering pins 70 descend against the urging force of the return springs74 and the neck presser plate 65 is driven down so that it moves awayfrom the underside of the core fixing plate 56 and pushes the neckfixing plate 64 downward. As a result, the core pins 52 of the injectioncore mold 50 are released from the preforms 1 whose neck portions 2 areheld by the neck cavity mold 60.

[0153] Preform Ejecting Section 16

[0154] Next, the construction of the preform ejecting section 16, and inparticular the preform ejection drive mechanism will be described. Inthis preferred embodiment, the preform ejection drive mechanism is madeup of a neck mold-release driver 80 and a split mold opening driver 100.As shown in FIG. 8, the neck mold-release driver 80 has a first cylinder82, and this first cylinder 82 is mounted on a first cylinder mountingplate 84 b supported on the upper clamping plate 22 by way of firstsupport rods 84 a. The first cylinder 82 drives a first raising andlowering plate 86 up and down by way of a first piston rod 82 a. Presserdrive rods 88 are provided at each end of this first raising andlowering plate 86. Holes 22 a are provided in the upper clamping plate22 passing through from the upper surface to the lower surface thereof,and the presser drive rods 88 are disposed in these holes 22 a. Theinitial position of the first raising and lowering plate 86 is aposition such that the ends of the presser drive rods 88 do not projectbelow the underside of the upper clamping plate 22 so they do notobstruct the rotation of the rotary disc 30.

[0155] As shown in FIG. 8, the rotary disc 30, the core presser plate 54and the core fixing plate 56 respectively have holes 30 a, 54 a and 56 ain positions facing the holes 22 a in the upper clamping plate 22.Driven rods 68 disposed in the holes 30 a, 54 a and 56 a are mounted onthe upper surface of the neck presser plate 65.

[0156] As a result, when the first cylinder 82 is driven, the neckpresser plate 65 and the neck fixing plate 64 are driven down againstthe urging force of the return springs 74 by the first cylinder 82 byway of the first piston rod 82 a, the presser drive rods 88 and thedriven rods 68. As shown in FIG. 10, this causes the core pins 52 of theinjection core mold 50 to release from the preforms 1 whose neckportions 2 are held by the neck cavity mold 60. In this preferredembodiment, the core pins 52 of the injection core mold 50 do not haveto be pulled completely clear of the open ends of the preforms 1, itonly being necessary that at least gaps through which air can enter formbetween the core pins 52 and the inner walls of the preforms 1. In thispreferred embodiment, the downward stroke of the neck fixing plate 64,that is the releasing stroke of the core pins 52 (the length L shown inFIG. 10), is set at for example 50 mm.

[0157] Next, the split mold opening driver 100 will be described. Asshown in FIG. 1 and FIG. 8, this split mold opening driver 100 has forexample two second cylinders 102. These second cylinders 102, as shownin FIG. 11, are mounted on a second cylinder mounting plate 104 bsupported on the first raising and lowering plate 86 by way of secondsupport rods 104 a. As a result, when the first raising and loweringplate 86 is driven up or down by the first cylinder 82, the secondcylinders 102 are also moved up or down at the same time. These secondcylinders 102 drive second raising and lowering plates 106 up and downby way of second piston rods 102 a. The split plate opening cams 108 aremounted on these second raising and lowering plates 106. The lower endportions of these split plate opening cams 108 are of a wedge shapefitting the wedge holes 64 d formed in the split plates 64 a and 64 bconstituting the neck fixing plate 64. By driving the second cylinders102 the split plate opening cams 108 are driven down and the wedgeportions at their ends are thereby inserted into the wedge holes 64 d inthe neck fixing plate 64, and this opens the split plates 64 a and 64 b.Consequently the pairs of split molds 62 a and 62 b mounted on this pairof split plates 64 a and 64 b are opened, and the preforms 1 are ejectedfrom the neck cavity mold 60. In this preferred embodiment the drivetiming of the second cylinders 102 is set to after the first cylinder 82is driven.

[0158] Next, the operation of the preform molding station 10 of theapparatus of the preferred embodiment will be described.

[0159] Injection Molding in Injection Molding Section 14

[0160] The clamping cylinder 28 is driven and the upper clamping plate22 is thereby driven down, whereby the injection core mold 50 and theneck cavity mold 60 are clamped to the injection cavity mold 42. Afterthe clamped state shown in FIG. 4 is reached, by a screw inside theinjecting apparatus 12 being advanced and rotated, the preforms 1injection molding material, for example polyethylene terephthalate(PET), is injected by way of the hot runner mold 40 into the cavitybounded by the molds 42, 50 and 60, and the preforms 1 are therebyinjection molded.

[0161] Cooling Step in Injection Molding Section 14

[0162] The injection cavity mold 42, the injection core mold 50 and theneck cavity mold 60 each have a coolant, for example water at roomtemperature, circulating through them, and the resin injected into thecavity bounded by the molds can be immediately cooled.

[0163] Injection Cavity Mold 42 Mold-Release Step in Injection MoldingSection 14

[0164] By the clamping cylinder 28 being so driven that it lifts theupper clamping plate 22, the injection core mold 50 and the neck cavitymold 60 can be lifted up away from the injection cavity mold 42 as shownby the mold-open state of FIG. 10. At this time, because the neckportions 2 of the preforms 1 form an undercut with respect to themold-release direction, the injection molded preforms 1 are held on theinjection core mold 50 and neck cavity mold 60 side and are releasedfrom the injection cavity mold 42.

[0165] The timing at which this mold-release starts in the injectionmolding section 14 can be made considerably earlier than a conventionalmold-release starting timing. In other words, the cooling time of thepreforms 1 in the injection molding section 14 can be shortened. This isbecause even after the preforms 1 have been released from the injectioncavity mold 42 the core pins 52 of the injection core mold 50 remaininside the preforms 1 and deformation of the preforms 1 accompanyingtheir thermal contraction can be prevented. Therefore, the mold-releasetemperature of the preforms 1 in the injection molding section 14 onlyhas to be low enough for a skin layer thick enough for the shape of thepreforms 1 to be maintained after they are released from the injectioncavity mold 42 to form at the outer surfaces of the preforms 1, and canbe higher than conventional mold-release temperatures. Even if themold-release temperature is high like this, because the cooling causesthe preforms 1 to contract around the core pins 52 of the injection coremold 50, mold-release from the injection cavity mold 42 can be carriedout relatively smoothly, and preform 1 mold-release problems do notoccur. Also, because in the injection molding section 14 withdrawal ofthe core pins 52 is not carried out, even if the preforms 1 aremold-released at a high mold-release temperature, the mold-releaseproblem of the lower ends of the preforms 1 being lifted together withthe core pins 52 does not occur.

[0166] The clamped state of the injection core mold 50 and the neckcavity mold 60 with respect to the preforms 1 released from theinjection cavity mold 42 is maintained by the core fixing plate 56 andthe neck presser plate 65 being kept in contact with each other by thereturn springs 74. This clamped state of the injection core mold 50 andthe neck cavity mold 60 is maintained through the subsequent preforms 1carrying step and until in the preform ejecting section 16 the injectioncore mold 50 is released from the preforms 1. Cooling of the preforms 1is possible throughout the time during which this clamped state of theinjection core mold 50 and the neck cavity mold 60 is maintained.

[0167] Preforms 1 Carrying Step

[0168] The preforms 1 are carried from the injection molding section 14to the preform ejecting section 16 by the rotary actuator 32 beingdriven and the rotary disc 30 constituting the first circulatory carrierbeing rotated thereby through 180°. During this preforms 1 carryingstep, it is possible for cooling of the preforms 1 by the coolantcirculating through the injection core mold 50 and the neck cavity mold60 to continue without interruption.

[0169] Generally, when the preforms 1 are mold-released at a hightemperature, crystallization occurs due to inadequate cooling and thewall surfaces of the preforms 1 become nontransparent, and particularlywhen PET is being used to make transparent containers this is a fataldefect. According to experiments carried out by the present inventors,this crystallization and loss of transparency of the preforms 1accompanying inadequate cooling is particularly marked at the inner wallsides of the preforms 1. This is because at the inner wall side of apreform 1 there is less surface area in contact with the mold andconsequently the inner wall is more liable to be inadequately cooledthan the outer wall. Also, when as in the past the injection cavity mold42 and the injection core mold 50 are released from the preforms 1 inthe injection molding section, the inner wall side is more liable to beinadequately cooled than the outer wall because the heat-radiatingsurface area at the inner wall side of the preform 1 is smaller than atthe outer wall side and furthermore heat is confined in the interior ofthe preform 1.

[0170] In this preferred embodiment, even if in the injection moldingportion 14 the preforms 1 are mold-released at a relatively hightemperature, in the subsequent carrying step it is possible for thepreforms 1 to continue to be cooled by the injection core mold 50 andthe neck cavity mold 60. In particular, because the inner walls of thepreforms 1 can be uninterruptedly cooled by the core pins 52 of theinjection core mold 50, crystallization and loss of transparency causedby inadequate cooling can be certainly prevented. Also, the neckportions 2, which because they are thick have large heat capacities andare more liable to crystallize than other portions, can be cooled by theneck cavity mold 60 and prevented from crystallizing.

[0171] Preform Cooling Step in Preform Ejecting Section 16

[0172] Even after the preforms 1 have been carried into the preformejecting section 16, by the clamped state of the injection core mold 50and the neck cavity mold 60 with respect to the preforms 1 beingmaintained, the preforms 1 can be cooled as they were during theabove-mentioned carrying step. At this time, even if in the injectionmolding section 14 the clamping cylinder 28 has been driven and theupper clamping plate 22 lowered for the injection molding of the nextpreforms, because the above-mentioned clamped state in the preformejecting section 16 is maintained, cooling of the preforms 1 can becontinued.

[0173] Separation of Neck Cavity Mold 60 from Injection Core Mold 50

[0174] Cooling of the preforms 1 by the core pins 52 of the injectioncore mold 50 only has to continue long enough for crystallization causedby inadequate cooling of the inner walls of the preforms 1 to beprevented and for deformation of the ejected preforms 1 to be avoided,and indeed if the preforms 1 are excessively cooled by the core pins 52,removal of the core pins 52 becomes difficult. Therefore, in thispreform ejecting section 16, first the injection core mold 50 isreleased from the preforms 1. In this preferred embodiment, this isachieved by the neck cavity mold 60 holding the preforms 1 beingreleased from the injection core mold 50.

[0175] This separation of the neck cavity mold 60 is carried out by theneck presser plate 65 kept in contact with the core fixing plate 56 bythe urging force of the return springs 74 being lowered by the neckmold-release driver 80. When the first cylinder 82 of the neckmold-release driver 80 is driven, the pushing force thereof transmittedthrough the first piston rod 82 a, the first raising and lowering plate86, the presser drive rods 88 and the driven rods 68 causes the neckfixing plate 64 to be pressed against the neck presser plate 65 and bedriven downward as shown in FIG. 6 and FIG. 10. At this time, becausethe preforms 1 have their neck portions 2 held by the neck cavity mold60, the preforms 1 are also driven downward together with the neckfixing plate 64 and the neck cavity mold 60. Consequently, theseparation of the neck cavity mold 60 from the injection core mold 50results in the injection core mold 50 being released from the preforms1.

[0176] This mold-releasing stroke of the injection core mold 50 withrespect to the preforms 1 does not have to be so long that the core pins52 are pulled completely clear of the open ends of the preforms 1 forthe subsequent carrying of the preforms 1 as it does conventionally, andneed only be long enough for at least gaps through which air can enterto be formed between the inner walls of the preforms 1 and the core pins52. Consequently, the mold-releasing stroke of the injection core mold50 depends on the angle of the removal taper provided on the core pins52 and the inner walls of the preforms 1, and the greater this removaltaper angle is, the shorter the mold-release stroke need be. Because themold-releasing stroke of the injection core mold 50 can be shortened inthis way the installation height of the first cylinder 82 can be madelow and the overall height of the injection molding apparatus can bemade low, and this is advantageous in the transportation andinstallation of the apparatus.

[0177] Preforms 1 Ejection Step in Preform Ejecting Section 16

[0178] Because the preforms 1 have their neck portions 2 held by theneck cavity mold 60 comprising the pairs of split molds 62 a and 62 b,the preforms 1 can be ejected by this neck cavity mold 60 beingreleased. To bring this about, the second cylinders 102 of the splitmold opening driver 100 are driven. This driving force of the secondcylinders 102 is transmitted to the split plate opening cams 108 by wayof the second piston rods 102 a and the second raising and loweringplates 106. By the split plate opening cams 108 being driven downward,as shown in FIG. 11 their ends are inserted into the wedge holes 64 dformed in the split plates 64 a and 64 b, these split plates 64 a and 64b are driven open, and the pairs of split molds 62 a and 62 b arethereby opened. At this time, even if a neck portion 2 of a preform 1has stuck to one of the split molds 62 a, 62 b and tries to movetherewith, because the respective core pin 52 of the injection core mold50 is still inside the preform 1, lateral movement of the preform 1 isrestricted and the preform 1 can be dropped downward without fail.

[0179] In the state before the split plate opening cams 108 are drivendownward, in order to avoid the split plate opening cams 108 interferingwith the rotation of the rotary disc 30 it is necessary that their endsstop within the thickness of the upper clamping plate 22. On the otherhand, because the neck fixing plate 64 which is driven open by thesesplit plate opening cams 108 is in the farthest position from the rotarydisc 30, the downward stroke of the split plate opening cams 108 islong. In this preferred embodiment, because the second cylinders 102which drive these split plate opening cams 108 are mounted on the firstraising and lowering plate 86 driven by the first cylinder 82 andbecause before the split plate opening cams 108 are driven the firstraising and lowering plate 86 is driven, the actual downward strokethrough which the split plate opening cams 108 are driven by the secondcylinders 102 is short. As a result, the installation height of thesecond cylinders 102 can be made low, the overall height of theinjection molding apparatus an be made low, and an apparatusadvantageous from the points of view of transportation and installationcan be provided.

[0180] After this preform 1 ejecting step is finished, the first andsecond cylinders 82 and 102 return to their original states. As aresult, the neck presser plate 65 is brought back into contact with thecore fixing plate 56 by the return springs 74, and the injection coremold 50 and the neck cavity mold 60 are returned to their clamped statein preparation for the next injection molding.

[0181] The cooling and mold-releasing steps described above carried outin the preform ejecting section 16 only have to be finished within thetime taken for the injection molding of the next, new preforms in theinjection molding section 14 to finish, in other words within theinjection molding cycle time. The preform 1 cooling time dependsparticularly on the thickness of the trunk portions of the preforms 1,and the thicker the preforms 1 are the longer the cooling time that mustbe provided. In this preferred embodiment this cooling time can beadjusted by way of the setting of the timing of the mold-release of theinjection core mold 50 in the preform ejecting section 16 as well as byadjusting the cooling time in the injection molding section 14. As aresult, even while the mold-release temperature in the injection moldingsection 14 is made high and the injection molding cycle time therebyshortened, because adjustment of the cooling time is easy a highlyflexible preform injection molding station can be provided.

[0182] After the preform 1 injection molding in the injection moldingsection 14 is finished, the injection core molds 50 and the neck cavitymolds 60 in the two sections 14 and 16 are changed around by the rotarydisc 30 being rotated through 180° by the rotary actuator 32. In thispreferred embodiment, the rotary actuator 32 consists of reversiblerotary carrying means of which the rotary carrying direction reverseseach time. As a result, even if the injection core molds 50 and the neckcavity molds 60 rotationally carried have cooling pipes for circulatingcoolant therethrough connected thereto, these cooling pipes will not betwisted through more than one revolution. Consequently, it is possibleto connect these cooling pipes to the molds without using rotaryconnectors and their construction does not become complicated.

[0183] Because for the reasons discussed above the preforms 1 are givena uniform temperature or a suitable temperature distribution, it ispossible to mold bottles of a desired thickness. Also, because whiteningcrystallization of the bottles is prevented, highly transparent bottlescan be molded. This invention is not limited to being applied to the hotparison blow molding described above, and of course can also be appliedto so-called cold parison blow molding wherein the preforms are returnedto room temperature before being heated again and blow molded. In thiscase also, there is the effect that the injection molding cycle time canbe shortened.

[0184] Transfer Station 200

[0185] Next, the constitution and operation of the transfer station 200will be described with reference to FIG. 2, FIG. 12 to FIG. 14 and FIG.21 and FIG. 22. FIG. 12 to FIG. 15 show a mechanism corresponding not tothe preferred embodiment apparatus shown in FIG. 1 but rathercorresponding to a preferred embodiment apparatus shown in FIG. 21. FIG.21 shows a case wherein the above-mentioned numbers N and n of preformsmolded simultaneously are respectively N=6 and n=2, and accordingly themechanisms of the transfer station 200 shown in FIG. 12 to FIG. 15transfer n=2 preforms 1 simultaneously. The case wherein n=1 preform 1is transferred at a time is exactly the same as the case where n=2except in that there is no transfer pitch conversion, which will befurther discussed later.

[0186] This transfer station 200 has a receiving and lowering mechanism210 which receives and lowers preforms 1 ejected from the preformejecting section 16 of the preform molding station 10, and an invertingand handing over mechanism 230 which then turns the preforms 1upside-down and hands them over to the preform receiving section 304 ofthe blow molding station 300.

[0187] Receiving and Lowering Mechanism 210

[0188]FIG. 12 and FIG. 13 respectively show the receiving and loweringmechanism 210 in a raised position and a lowered position. Thisreceiving and lowering mechanism 210 has a bottom portion holding part214 which holds the bottom portion 3 of a preform 1 and a neck lowerportion holding part 218 which supports a support ring 2 a formed at thelower end of the neck portion 2 of the preform 1. The bottom portionholding part 214 is mounted on a rod 212 a of a first raising andlowering drive device 212 comprising an air cylinder or the like and ismovable up and down between the raised position in which it is shown inFIG. 12 and the lowered position in which it is shown in FIG. 13. Thisvertical stroke b is shown in FIG. 4.

[0189] The neck lower portion holding part 218 is movable up and downtogether with the bottom portion holding part 214 and is movablehorizontally through a horizontal stroke a shown in FIG. 4. To make thispossible, a first slider 220 is disposed on a rail 222 slidablytherealong. This first slider 220 is driven horizontally by a rod 216 aof a first advancing and withdrawing drive device 216 comprising an aircylinder or the like. The neck lower portion holding part 218 has asmall diameter shaft portion 218 a at its lower part and a largediameter shaft portion 218 b at its upper part, and the small diametershaft portion 218 a passes through a stopper member 220 a mounted on thefirst slider 220. A flange 218 c is fixed to the lower end of the smalldiameter shaft portion 218 a which projects below this stopper member220 a. Also, a spring 218 d is disposed around a portion of the smalldiameter shaft portion 218 a projecting upward of the bottom portionholding part 214. Because this spring 218 d is disposed between thebottom portion holding part 214 and the large diameter shaft portion 218b, the large diameter shaft portion 218 b is pushed upward by the spring218 d as the bottom portion holding part 214 ascends, and the neck lowerportion holding part 218 can thereby be raised. When the first advancingand withdrawing drive device 216 is driven, because this horizontaldriving force is transmitted by way of the first slider 220 to the shaftportions 218 a and 218 b, the neck lower portion holding part 218 iscaused to slide horizontally. This sliding stroke a is shown in FIG. 4.

[0190] The operation of this receiving and lowering mechanism 210 willnow be explained with reference to FIG. 4, FIG. 12 and FIG. 13. Beforethe neck cavity mold 60 is driven open in the preform ejecting section16 of the preform molding station 10, the bottom portion holding part214 and the neck lower portion holding part 218 are disposed in thepositions in which they are shown in FIG. 12. In this state shown inFIG. 12, the raised position of the neck lower portion holding part 218is determined by the flange 218 c thereof abutting with the stoppermember 220 a. The bottom portion holding part 214 is stopped in aposition which it reaches by compressing the spring 218 d after the necklower portion holding part 218 has reached its upper limit position. Atthis time, the neck lower portion holding part 218 is in a positionwherein it is withdrawn to the right in FIG. 4 and FIG. 12 of a positiondirectly below the support ring 2 a of the preform 1. When the neckcavity mold 60 is driven open, the preform 1 drops downward and itsbottom portion 3 is caught by the bottom portion holding part 214. Atthis time, as shown in FIG. 12, the preform 1 does not completelyrelease from the core pin 52 and the preform 1 maintains an uprightstate with a portion of the core pin 52 remaining inserted therein.

[0191] After that the first advancing and withdrawing drive device 216is driven, and the neck lower portion holding part 218 is moved to theleft through the stroke a (see FIG. 4). As a result, the neck lowerportion holding part 218 is positioned directly below the support ring 2a of the preform 1.

[0192] After that, the first raising and lowering drive device 212 is sodriven that it pulls in the rod 212 a, and the bottom portion holdingpart 214 starts to be lowered. In the initial stage of this lowering,until the spring 218 d returns to its original length, the neck lowerportion holding part 218 stays in its upper position. As a result,during the initial stage of this lowering, the bottom portion holdingpart 214 moves away from the bottom portion 3 of the preform 1 and thesupport ring 2 a of the preform 1 comes to rest on the neck lowerportion holding part 218. The first raising and lowering drive device212 continues to be driven after this, and the preform 1 descends withits support ring 2 a being held by the neck lower portion holding part218 only. It is preferable that members of low thermal conductivity, forexample synthetic resin or the like, be used for the portions of thebottom portion holding part 214 and the neck lower portion holding part218 which make contact with the preform 1. The preform 1 supported bythe neck lower portion holding part 218 continues to be lowered until itreaches the position in which it is shown in FIG. 13.

[0193] Inverting and Handing Over Mechanism 230

[0194] Next, the constitution of the inverting and handing overmechanism 230 will be described with reference to FIG. 4 and FIG. 13 toFIG. 15. This inverting and handing over mechanism 230 has two neckholding mechanisms 232 corresponding to the number n=2 of preformssimultaneously blow molded in the blow molding section 310 shown in FIG.21 (see FIG. 14). The neck holding mechanisms 232 each have anopen/closeable pair of neck holding members 234 which hold the neckportion 2 of the preform 1. As shown in FIG. 15, these two neck holdingmechanisms 232 are mounted on a support table 236, and this supporttable 236 is linked to a rod 238 a of a second raising and loweringdrive device 238 comprising and air cylinder or the like. As a result,the two neck holding mechanisms 232 are movable vertically through avertical stroke e shown in FIG. 4. In order to make this verticalmovement smooth, for example two guide rods 240 are provided and guidedby guide portions 242.

[0195] The second raising and lowering drive device 238 and the guideportions 242 described above are mounted on a second slider 244 as shownin FIG. 15. This second slider 244 is provided with a horizontal drivedevice 246 which moves the second slider 244 in the direction in whichthe number of preforms N, for example 4, simultaneously molded in theinjection molding section 14 are arrayed. This horizontal drive device246 moves the second slider 244 horizontally by means of for example aball screw 246 a. The horizontal drive device 246 is mounted on a thirdslider 248, and this third slider 248 is provided with a secondadvancing and withdrawing drive device 250 which advances and withdrawsthe raising and lowering drive device 238 through the advancing andwithdrawing stroke c shown in FIG. 4. That is, as shown in FIG. 14, arod 250 a of the second advancing and withdrawing drive device 250 islinked to the third slider 248.

[0196] Also, there is provided an inverting drive device 252 whichrotates the two neck holding mechanisms 232 through 180° about ahorizontal axis. The 180° rotational stroke d of this inverting drivedevice 252 is shown in FIG. 4. As a result of this inversion the preform1 moves from an upright state wherein the neck portion 2 faces upward toan inverted state wherein the neck portion 2 faces downward.

[0197] Next, the operation of this inverting and handing over mechanism230 will be explained. When the preforms 1 reach their lowered positionsas shown in FIG. 13, the neck holding mechanisms 232 which are in astandby position shown with chain lines in FIG. 13 are rotated through180° by the inverting drive device 252. Opening and closing drivemechanisms incorporated into the neck holding mechanisms 232 close thepairs of neck holding members 234, and the neck portions 2 of thepreforms 1 are held by these neck holding members 234. Then the preforms1 are inverted. Before that, however, to prevent the preforms 1 frominterfering with other members, the neck lower portion holding part 218is withdrawn to the right through the moving stroke a (see FIG. 4), andby the third slider 248 being moved to the left through the movingstroke c (see FIG. 4) the two neck holding mechanisms 232 are moved tothe left. After that, by the preforms 1 being rotated through 180° bythe inverting drive device 252, the preforms 1 reach the position shownwith chain lines in FIG. 13. Then, by the two neck holding mechanisms232 being lowered by the second raising and lowering drive device 238through the stroke e (see FIG. 4), the preforms 1 can be placed oncarrier members 330 positioned in the preform receiving section 304 ofthe blow molding station 300. After that, the neck holding mechanisms232 are opened and moved through the vertical stroke e and thetransverse stoke c shown in FIG. 4 whereby the neck holding mechanisms232 are moved away from the preforms 1 and returned to their standbyposition shown with chain lines in FIG. 13.

[0198] When the above transfer operation is carried out in the preferredembodiment apparatus shown in FIG. 21 wherein the number ofsimultaneously blow molded preforms 1 is n=2, n=2 preforms 1 aretransferred simultaneously. The transferred two preforms 1 are handedover to carrier members 330 in two receiving positions 260. At thistime, the pitch P2 at which the neck holding mechanisms 232 receive thetwo preforms 1 from the receiving and lowering mechanism 210 isdifferent from the pitch P3 at which the neck holding mechanisms 232deliver the two preforms 1 to the carrier members 330. This is becauseduring the transfer of the preforms 1 pitch conversion is performed by apitch change drive device 254; this point will be further discussedlater. In the case of the preferred embodiment apparatus of FIG. 1wherein the number of preforms 1 simultaneously blow molded is n=1, thepreform 1 is delivered to a carrier member 330 positioned between thetwo receiving positions shown in FIG. 14. Therefore, each time aninjection molding operation in which N=4 simultaneously injection moldedpreforms 1 are injection molded is finished, transfer of one preform 1at a time is repeated four times.

[0199] Blow Molding Station 300

[0200] Next, the blow molding station 300 will be described withreference to 41, FIG. 4 and FIG. 16 to FIG. 20.

[0201] Second Circulatory Carrier 302 and Preform Receiving Section 304

[0202] This blow molding station 300 circulates the carrier member 330carried by the second circulatory carrier 302 in order through thepreform receiving section 304, the heating section 306, the standbysection 308, the blow molding section 310 and the bottle ejectingsection 312. As shown in FIG. 1, the second circulatory carrier 302 hasfour sprockets 320 a to 320 d, and for example only the sprocket 320 ais driven and the other sprockets 320 b to 320 d are not driven. Anendless carrier chain 322 runs around these four sprockets 320 a to 320d. Some other endless drive member, such as a belt, for example a V-beltor a toothed belt, can be used instead of the chain, and other rotarydrive members such as pulleys can be used instead of the sprockets.

[0203] In the preferred embodiment apparatus shown in FIG. 1, tencarrier members 330 are fixed to the carrier chain 322. This fixingstructure is as follows:

[0204] As shown in FIG. 18, each carrier member 330 has a cylindricalmount portion 332. This mount portion 332 has is provided at one sidethereof with projecting portions 334 a and 334 b which respectivelyproject above and below the carrier chain 322, sandwiching the carrierchain 322. Adjacent chain links in the carrier chain 322 are connectedby hollow pins, and the upper and lower projecting portions 334 a and334 b are linked to the carrier chain 322 by fixing pins 336 beingpassed through the central portions of the hollow pins and having theirends secured so that they cannot drop out.

[0205] A cylinder 342 is rotatably supported by way of a bearing 340inside the cylindrical portion of the mount part 332. The upper portionof this cylinder 342 functions as a carrying surface 344 on which theend surface of the neck portion 2 of an inverted preform 1 is placed.Also, a carrying pin 346 is supported inside this cylinder 342. Thiscarrying pin 346 has a portion thereof projecting upward of the carryingsurface 344 which enters the neck portion 2 of the preform 1 and cansupport the preform 1 in its inverted state. Thus, the carrying surface344 and the carrying pin 346 constitute a preform 1 supporting portion.

[0206] As shown in FIG. 16, three cam followers 338 consisting ofrollers or the like are supported on this carrier member 330. Two of thecam followers 338 roll along the inner side locus described when thecarrier member 330 is driven by the carrier chain 322. The other camfollower 338 rolls along the outer side locus. These three cam followers338 are guided by a carrier base 324 or by rails 326, depending on wherethe carrier member 330 is in the blow molding station 300. As shown inFIG. 18, the two rails 326 are disposed on either side of the carryingpath and each are formed with a C-shaped cross-section and have a camsurface 326 a. These rails 326 have portions which so project that theycover the upper portions of the cam followers 338, and the cam followers338 cannot leave the rails 326. These rails 326 are disposed in the blowmolding section 310.

[0207] On the other hand, in all parts of the carrying path outside theblow molding section 310, for example as shown in FIG. 19 showing theheating section 306, the carrier base 324 is provided below the carryingpath. Upper surfaces of this carrier base 324 constitute cam surfaces324 a. Portions of the rails 326 disposed in the heating section 306 areso disposed that they cover the upper portions of the cam followers 338and prevent the cam followers 338 from escaping from their travel paths.Because if the carrier base 324 were provided in the blow moldingsection 310 it would not be possible for a drawing rod and a blow coremold to be inserted from below into the preform 1, such a constructionis not used.

[0208] An autorotation sprocket 348 is mounted on the cylinder 342 ofthe carrier member 330. When the preform 1 is in the heating section306, this autorotation sprocket 348 rotates the preform 1 about itsvertical axis; this point will be further discussed in the descriptionof the heating section 306.

[0209] The driving sprocket 320 a repeats an intermittent carryingmovement wherein it moves by an amount corresponding to one pitch of thecarrier members 330 fixed to the carrier chain 322 at a predeterminedpitch and then stops for a predetermined period of time. By the preform1 being received in an inverted state by the preform receiving section304 of the blow molding station 300 the preform 1 is placed on thecarrying surface 344 of the carrier member 330 and the carrying pin 346is inserted into the neck portion 2 of the preform 1. When after thatthe driving sprocket 320 a is driven and rotates, the carrier chain 322meshing with the sprockets 320 a to 320 d moves and the carrier members330 are thereby moved by one pitch. By this carrying operation beingrepeated, the preforms 1 received in the preform receiving section 304are carried through the heating section 306 and the standby section 308to the blow molding section 310, and here they are drawn and blow moldedinto bottles 6. After that the bottles 6 on the carrier members 330 arecarried to the bottle ejecting section 312, and here the bottles 6 areejected to outside the apparatus.

[0210] Heating Section 306

[0211] Next, the heating section 306 will be described with reference toFIG. 19 and FIG. 20.

[0212] The heating section 306 heats the preform 1 by means of radiantheat in a space enclosed by a heating box cover 350. As described above,in the apparatus of this preferred embodiment, the preform 1 can beamply cooled by the injection core mold 50 while it is being carried tothe preform ejecting section 16 and in the preform ejecting section 16until the injection core mold 50 is released from the preform 1. As aresult, while the method is still a hot parison method, the preform 1can be amply cooled and can be cooled to a temperature lower than issuitable for blow molding. For this reason, in the apparatus of thispreferred embodiment, the preform 1 is heated in the heating section 306provided in the blow molding station 300 until it reaches a temperaturesuitable for blow molding.

[0213] Inside the heating box cover 350 of the heating section 306 thereare provided first to fourth barlike heaters 352 a to 352 d constitutinga first heater set disposed spaced apart in the axial direction of thepreform 1. The barlike heaters 352 a to 352 d are for example infraredheaters, and extend in the preform 1 carrying direction inside theheating box cover 350. The first and second barlike heaters 352 a and352 b are partly surrounded by a focussing reflecting plate 354 a, andheat especially the bottom portion 3 of the preform 1 with radiant heat.The third and fourth barlike heaters 352 c and 352 d are partlysurrounded by a focussing reflecting plate 354 b and heat especially thevicinity of the trunk portion 4 of the preform 1 with radiant heat. Asshown in FIG. 19, a reflecting plate 356 is disposed on the other sideof the carrying path facing the barlike heaters 352 a to 352 d.

[0214] Also, as shown in FIG. 19, fifth and sixth barlike heaters 352 eand 352 f constituting a second heater set are disposed one on eitherside of the preform 1 carrying path. These barlike heaters 352 e and 352f are positioned at such a vertical height that they face the vicinityof the neck portion 2 of the preform 1 which is draw orientated in theblow molding section 310. The region of the preform 1 heated by thesefifth and sixth barlike heaters 352 e and 352 f is the region which isimmediately below the neck portion 2 when the preform 1 is upright, andwill hereinafter be called the region below the neck 4 a.

[0215] This region below the neck 4 a is the region corresponding to theshoulder portion of the blow molded bottle 6. Consequently, when thepreform 1 is positioned inside the blow mold 378, this region below theneck 4 a is in the position closest to the surface of the blow cavity.Because of this, because the transverse axis orientation rate is low,the region below the neck 4 a tends to become thick, but by amplyheating the region below the neck 4 a it is possible for it to be moldedto the desired thinness. To this end, in this preferred embodiment, aswell as the fifth and sixth barlike heaters 352 e and 352 f beingdisposed in positions where they face the region below the neck 4 a ofthe preform 1, the heat-radiating surfaces of these heaters are disposedcloser to the region below the neck 4 a than the other heaters are tothe preform 1.

[0216] As shown in FIG. 20, two sprockets 360 a and 360 b are disposedinside the heating box cover 350 of this heating section 306, and anautorotation drive chain 358 runs around these two sprockets 360 a and360 b. This autorotation drive chain 358 also meshes with theautorotation sprocket 348 on the carrier member 330 that has beencarried into the heating section 306. As a result of this arrangement,when the autorotation drive chain 358 is driven, the autorotationsprocket 348 rotates, this rotation is transmitted by way of thecylinder 342 to the preform 1, and the preform 1 is rotated.

[0217] As a result, when the preform 1 is carried into the heatingsection 306, the bottom portion 3 and the trunk portion 4 of the preform1 receive radiant heat both from the barlike heaters 352 a to 352 ddisposed on one side of the carrying path and from the reflecting plate356 disposed on the other side of the carrying path, and because thepreform 1 is rotated it receives heat substantially uniformly in thecircumferential direction and therefore is heated uniformly in thecircumferential direction. Also, the region below the neck 4 a of thepreform 1 is amply heated by the fifth and sixth barlike heaters 352 eand 352 f disposed close to the preform 1 on either side of the carryingpath, and furthermore the rotation of the preform 1 ensures that thisregion below the neck 4 a also is heated substantially uniformly in thecircumferential direction.

[0218] Here, as shown in FIG. 20, when the preform 1 carrying directionis direction A, the direction of travel of the autorotation drive chain358 where it meshes with the autorotation sprocket 348 of the carriermember 330 is made direction B, the opposite direction to direction A.The reason for this is as follows:

[0219] If the carrier chain 322 and the autorotation drive chain 358were both to move at the same speed and in the same direction, directionA, there would be no relative movement between the autorotation sprocket348 on the carrier member 330 side and the autorotation drive chain 358,and the preform 1 would not rotate at all. Even if the running speeds ofthe carrier chain 322 and the autorotation drive chain 358 were to bechanged, depending on the sizes of the speeds the rotation of thepreform 1 would either be extremely slow or would be reverse rotation.These situations will not occur if the autorotation drive chain 358 isdriven at a higher speed than the carrier chain 322, but normally it isnot desirable to rotate it at high speed in this way for reasonsrelating to moment. When rotated at high speed, if the preform 1 isslightly bent, this bend will be made greater by the strong moment itundergoes and this will cause uneven heating of the preform 1 andadversely affect the thickness distribution of the bottle 6.

[0220] Therefore, in the preferred embodiment shown in FIG. 20, byhaving the carrier chain 322 and the autorotation drive chain 358 run inopposite directions, when the preform 1 is carried in direction A thedirection of its autorotation will always be the arrow C direction, andthe problems described above are eliminated. The preform 1 rotatesfaster while it is being moved than when it is at a preform 1 stoppingposition.

[0221] Also, in this preferred embodiment, the total number ofrevolutions through which the preform 1 is rotated while it is insidethe heating zone inside the heating box cover 350 is made asubstantially integral number. In this preferred embodiment, while thepreform 1 is in the heating zone refers to the time that the preform 1spends moving through the distances L1, L2 and L3 (L1+L2+L3=the heatingzone length L), as shown in FIG. 20, and the time the preform 1 spendsstopped at the two positions shown in FIG. 20. L1 is the distance overwhich the preform 1 is carried between entering the heating zone and thefirst stopping position; L2 is the distance between the two stoppingpositions; and L3 is the distance over which the preform 1 is carriedbetween the second stopping position and leaving the heating zone. Inthis preferred embodiment, by making the number of turns through whichthe preform 1 autorotates in this carrying time and stopped time asubstantially integral number of turns, the radiant heat from both sidesof the preform 1 carrying path can be received substantially uniformlyin the circumferential direction of the preform 1 and temperaturevariation in the circumferential direction of the preform 1 can therebybe prevented.

[0222] Also, according to this preferred embodiment, the operation ofheating the preform 1 in this heating section 306 can be carried outafter any temperature difference between the inner wall and the outerwall of the preform 1 has been sufficiently reduced. That is, in thispreferred embodiment, the preform 1 is amply cooled from the inner wallside thereof by the injection core mold 50 in the preform moldingstation 10. As a result, the inner wall temperature of the preform 1ejected in the preform ejecting section 16 is low, and the outer walltemperature is high. However, this preform 1 does not immediately enterthe heating section after a short carrying period as in the case of aso-called hot parison or 1-stage apparatus but rather enters the heatingsection 306 after being transferred by the transfer station 200 andcarried stepwise by the carrier member 330. As a result, after thepreform 1 is released from the injection molds, a considerably longercooling time elapses than in a so-called 1-stage apparatus before thepreform 1 enters the heating section 306. Because of this, thedifference between the temperatures of the inner and outer walls of thepreform 1 can be amply moderated. This lack of temperature differencebetween the inner and outer walls is the same as in so-called coldparison or 2-stage apparatuses, but because unlike the case in theseapparatuses the bottle 6 in this preferred embodiment can be blow moldedfrom a preform 1 still containing heat from when it was injectionmolded, the preferred embodiment is superior in that less heat energyhas to be given to the preforms and therefore energy can be saved.

[0223] Furthermore, with this preferred embodiment, by heating controlof preforms 1 cooled to a temperature lower than a blow moldingtemperature (but considerably higher than room temperature), thestability of the preform temperature from molding cycle to molding cycleis improved and it is possible to reduce the variation in temperatureoccurring when a plurality of simultaneously injection molded preforms 1are blow molded non-simultaneously. Also, in the apparatus of thispreferred embodiment, the carrying pitch at which the preforms 1 arecarried by the second circulatory carrier 302 is maintained at a fixedpitch. In contrast to this, in conventional cold parison or 2-stagemolding machines, the carrying pitch is made smaller when the preformsare heated in the heating section and the carrying pitch is made largerwhen they enter the blow molding section. The reason why the carryingpitch is made smaller in the heating section is that because it isnecessary to heat the preforms all the way from room temperature to theblow molding temperature the total number of preforms inside the heatingsection is made as large as possible in order to keep the apparatus assmall as possible. The reason why the carrying pitch is made larger inthe blow molding section, on the other hand, is that when a plurality ofpreforms are to be blow molded simultaneously the distance between thepreforms has to be made at least greater than the maximum width of themolded product. Also, preforms about to be carried into the blow moldingsection and preforms having just been carried out of the blow moldingsection have to standby outside the blow mold clamping apparatus of theblow molding section. Because of this, in conventional 1-stage moldingmachines the carrying pitch has to be changed midway around the carryingpath and the apparatus consequently is complex.

[0224] In contrast with this, in this preferred embodiment apparatus,because bottles 6 are blow molded from preforms 1 which still containheat from when they were injection molded in the injection moldingsection 14, the amount of heat energy which has to be given to thepreforms 1 in the heating section 306 is very small compared to a2-stage case. As a result, the preforms 1 can be fully reheated to theblow molding temperature without the total number of preforms 1 in theheating section 306 being increased, and it is not necessary for thecarrying pitch to be changed midway around the carrying path.

[0225] Standby Section 308

[0226] As shown in FIG. 1, in the carrying path between the heatingsection 306 and the blow molding section 310, one stop of the preform 1performed by the normal carrying sequence carrying out intermittentdrive is allocated to the standby section 308. The provision of thisstandby section 308 makes it possible to moderate the temperaturedistribution in the preform 1, which, being made of a synthetic resin,has poor thermal conductivity. Like the heating in the heating section306 in this preferred embodiment apparatus, the heating of the preform 1is normally carried out from the outside using radiant heat. Because ofthis, the temperature of the inner wall of the preform 1 becomes lowerthan the temperature of the outer wall. In the apparatus of thispreferred embodiment, after the preform 1 is carried out of the heatingsection 306, by stopping the preform 1 at least once in the standbysection 308 before it is carried into the blow molding section 310 it ispossible to reduce this temperature difference between the inner andouter walls and the blow molding characteristics of the bottle 6 canthereby be stabilized.

[0227] During this temperature distribution moderation in the standbysection 308 it is also possible to perform temperature adjustment of thepreform 1 actively. By actively performing temperature adjustment of thepreform 1 in the standby section 308 it is possible to obtain atemperature distribution which cannot be obtained just by heating thepreform 1 while rotating it in the heating section 306.

[0228] As a temperature adjusting member disposed in the standby section308, for example a temperature adjusting core 400 which is inserted frombelow the preform 1 into the preform 1 and performs temperatureadjustment from the inner wall side over a temperature adjustment regionS can be used, as shown in FIG. 23. This temperature adjusting core 400has a first temperature adjusting core 402 which performs temperatureadjustment of the region below the neck 4 a of the preform 1 from theinner wall side thereof. This temperature adjusting core 400 also has asecond temperature adjusting core 404 which performs temperatureadjustment on the trunk portion excluding the region below the neck 4 a.As described above, because it is necessary to adjust the temperature ofthe region below the neck 4 a to a higher temperature than otherregions, in FIG. 23 the first temperature adjusting core 402 has alarger diameter than the second temperature adjusting core 404.Alternatively, a layer consisting of a material which radiates heat ofsuch a wavelength that it is easily absorbed by the resin material fromwhich the preforms 1 are molded (for example PET) may be coated onto thefirst temperature adjusting core 402.

[0229] As shown in FIG. 24, the temperature adjusting member can also bemade a temperature adjusting pot 410 having a cylindrical portion whichcan be positioned around the preform 1. In this case, the temperatureadjusting pot 410 has blocks 414 a to 414 d divided into zones in theaxial direction of the preform 1 by thermal insulation 412, and each ofthe blocks 414 a to 414 d has an independent temperature adjusting fluidpassage 416 whereby independent temperature control of each zone iscarried out. Because the temperature adjusting pot 410 can be sopositioned that is covers the preform 1, a temperature distributionstepped in the axial direction of the preform 1 can be certainlyobtained. By this means, it is possible to for example adjust the regionbelow the neck 4 a to a high temperature and adjust the bottom portion 3to a low temperature. As shown in FIG. 14, it is also possible to applyan internal pressure to the preform 1 by introducing air into thepreform 1 in the direction of the arrow 420 and thereby bring the outerwall of the preform 1 and the blocks 414 a to 414 d into contact andfacilitate the temperature adjustment.

[0230] Also, as this kind of temperature adjusting member, it ispossible to use a member which in one or a plurality of locations in thecircumferential direction of the preform 1 extend in the axial directionof the preform 1 and impart the preform 1 with a temperaturedistribution in the circumferential direction thereof. For example, asshown in FIG. 25, it is possible for example at both sides of thepreform 1 to dispose a pair of cooling members 430 along the axialdirection of the preform 1 and bring them into contact with the sidewall of the trunk portion of the preform 1 using air cylinders 432 orthe like. When this is done, the preform 1 is given a temperaturedistribution in the circumferential direction, and for example as shownin FIG. 26 it is possible to fully secure the wall thickness required ofthe high transverse axis drawing rate region of a flat bottle 6. Thiskind of measure can be applied not only to flat containers but also tofor example square containers. When a temperature distribution in thecircumferential direction of the preform 1 is to be imparted, besidesbringing a cooling member into contact with the preform 1 it is alsopossible to position a heating member in the vicinity of the preform 1.

[0231] Blow Molding Section 310

[0232] The blow molding section 310 has two blow mounting plates 370mounted on the machine bed 8, one on either side of the preform 1carrying path. As shown in FIG. 4, for example four tie bars 372 aremounted crossing between these two blow mounting plates 370. Two blowmold clamping plates 374 which move horizontally along the four tie bars372 are mounted between the blow mounting plates 370. These two blowmold clamping plates 374 are opened and closed symmetrically about avertical line by a blow mold clamping mechanism 376, comprising forexample hydraulic pistons, mounted on the blow mounting plates 370.

[0233] A pair of split molds 378 a and 378 b constituting the blow mold378 are mounted on these two blow mold clamping plates 374. In the caseof the preferred embodiment apparatus shown in FIG. 1, because thenumber n of bottles simultaneously blow molded is n=1, a cavity for onebottle is formed in the pair of split molds 378 a and 378 b. In the caseof the preferred embodiment apparatus shown in FIG. 21, because thenumber n of bottles simultaneously blow molded is n=2, cavities for twobottles are formed in the pair of split molds 378 a and 378 b.

[0234] A cylinder mounting plate 380 is mounted at a position midwayalong the upper two tie bars 372, and a bottom mold driving cylinder 382is mounted on this cylinder mounting plate 380. This bottom mold drivingcylinder 382 raises and lowers a bottom mold 384. In this preferredembodiment, because the bottle 6 is blow molded from a preform 1 whichis inverted, the bottom mold 384 is made movable up and down above thepreform 1.

[0235] Thus in this preferred embodiment, while raising productivity byinjection molding N=4 preforms 1 simultaneously in the injection moldingsection 14 of the preform molding station 10, by only molding n=1 bottle6 at a time in the blow molding section 310 it is possible to raise theoperation rate of the blow cavity mold 378. Also, by reducing the numberof cavities in the blow cavity mold 378, which is a relatively expensivetype of mold, mold costs, molds being consumable items, can be reduced.Furthermore, in this preferred embodiment apparatus, because in thepreform molding station 10 the preforms 1 are amply cooled before theyare released from the injection molds, and because enough cooling timeis provided thereafter for the temperature difference between the innerand outer walls of the preforms 1 to be moderated before the preforms 1are heated to the blowing temperature, the uniformity of the temperaturedistribution of the retained heat in the preforms 1 can be increased andthe stability of the blow molding can be greatly improved.

[0236] Bottle Ejecting Section 312

[0237] As shown in FIG. 1 and FIG. 4, the bottle ejecting section 312 isdisposed in the carrying path of the carrier members 330 carried by thesecond circulatory carrier 302 between the blow molding section 310 andthe preform receiving section 304. This bottle ejecting section 312 hasa neck holding mechanism 390 having for example a similar constructionto that of the neck holding mechanisms 232 employed in the inverting andhanding over mechanism 230. This neck holding mechanism 390 holds theneck portion of the inverted bottle 6 by means of a pair of holdingmembers. As shown in FIG. 3 and FIG. 4, there are also provided araising and lowering drive device 392 which raises and lowers this neckholding mechanism 390 and an inverting drive device 394 which invertsthe neck holding mechanism through an angle of 180°. By the neck holdingmechanism 390 being raised by the raising and lowering drive device 392,the neck portion of the bottle 6 is pulled upward off the carrying pin346 of the carrier member 330. After that, by this holding mechanism 390being rotated through 180° by the inverting device 394, the bottle 6 isbrought into an upright state to one side of the machine bed 8, and bythe pair of holding members of the neck holding mechanism then beingopened, the bottle 6 is discharged to outside the apparatus.

[0238] When Simultaneous Molding Numbers Are N=6, n=2

[0239]FIG. 21 is a plan view of a preferred embodiment apparatus whereinthe simultaneous molding numbers are N=6, n=2. The preferred embodimentshown in FIG. 21 differs from the preferred embodiment apparatus shownin FIG. 1 in the following points:

[0240] First, because the blow molding section 310 is to simultaneouslyblow mold two bottles 6 at a time from among the N=2 simultaneouslyinjection molded preforms, the blow cavity mold 378 has two blowcavities spaced an array pitch P3 apart. The array pitch at which thecarrier members 330 carried by the second circulatory carrier 302 arespaced apart is the same pitch as the array pitch P3 of the blowcavities in the blow molding section 310. Also, the total number ofcarrier members fitted to the carrier chain 322 constituting the secondcirculatory carrier 302 is twenty, twice as many as in the case of thepreferred embodiment shown in FIG. 1. Enough preforms 1 for two blowmolding cycles, 2×n=4 preforms 1, are stopped inside the heating section306. In the standby section 308, enough preforms 1 for one blow moldingcycle, n=2 preforms 1, are made to standby. The carrier chain 322 andthe carrier members 330 used in the preferred embodiment apparatus ofFIG. 21 are the same as those used in the preferred embodiment apparatusshown in FIG. 1, and it is only the positions and pitch at which thecarrier members 330 are fitted to the carrier chain 322 that aredifferent.

[0241] In the preferred embodiment apparatus shown in FIG. 21, in thetransfer station 200, the number n=2 of preforms 1 simultaneously blowmolded in the blow molding section 310 are simultaneously transferred.For this, a transfer pitch converting operation, which will now beexplained with reference to FIG. 22, is necessary. In FIG. 22, sixpreforms 1 simultaneously injection molded in the injection moldingsection 14 of the preform molding station 10 are shown as preform 1 a topreform 1 f. In FIG. 22, the first row on the right shows the arraypitch of the preforms 1 injection molded in the preform molding station10. The array pitch of the preforms 1 at this time is the same as thearray pitch P1 of the core pins 52 of the injection molding section 14.The second row from the right in FIG. 22 shows the state of the preforms1 before they are received by the inverting and handing over mechanism230 of the transfer station 200. The array pitch of the preforms 1 hereis also the pitch P1. The third row from the right in FIG. 22 shows thestate of two preforms 1 received by the preform receiving section 304 ofthe blow molding station 300. The transfer of these two preforms 1 iscarried out using the two pairs of neck holding members 234 shown inFIG. 4. The array pitch of the preforms 1 received by the preformreceiving section 304 is the same as their array pitch P3 in the blowmolding section 310.

[0242] Here, in the transfer station 200, when the two preforms 1 aretransferred by the two pairs of neck holding members 234, first, forexample the first and fourth preforms 1 a and 1 d are held. That is, thetwo preforms 1 a and 1 d are held and the two preforms 1 b and 1 c areignored this time. As a result, the array pitch P2 of the neck holdingmembers 234 at this time is P2=3×P1. This pitch conversion from thepitch P2 to the pitch P3 is carried out by the array pitch of the twoneck holding mechanisms 232 being converted by the pitch change drivedevice 254 shown in FIG. 14. Similarly thereafter, by the second andfifth preforms 1 b and 1 e being transferred and then the third andsixth preforms 1 c and if being simultaneously transferred after that,the operation of transferring of the six simultaneously molded preforms1 is completed.

[0243] When the simultaneous molding numbers N, n are made N 4, n=2, thetransfer operation in the transfer station 200 is carried out with pitchconversion from the pitch P2=2×P1 to the pitch P3 being performed andtwo preforms being held while the one preform between them is ignoreduntil the next time.

[0244] In the case of the preferred embodiment apparatus shown in FIG.21, the ratio (N/n) of the simultaneous molding numbers N and n is 3.According to studies carried out by the present inventors, in the caseof general-purpose medium-sized containers of capacity about 1 to 3liters having relatively small mouths (the diameter of the opening ofthe neck portion 2 being about 28 to 38 mm), the ratio of thesimultaneous molding numbers N, n should ideally be set to N:n=3:1. Thereason for this is as follows: The size of a preform for molding ageneral-purpose medium-sized container, although some elements do varyaccording to the application, is within a substantially fixed range.This is because the preform size is determined by the drawing factornecessary to obtain the drawing characteristics of polyethyleneterephthalate (PET) resin and the drawing factor necessary for moldingstability. Although there is some variation depending on the use forwhich the container is intended, research carried out by the presentinventors has shown that the maximum thickness of the trunk portion 4 ofa preform 1 used for a general-purpose medium-sized container lieswithin the range 3.0 to 4.0 mm.

[0245] Generally, the blow molding cycle time (the time required betweenwhen a preform 1 is carried into the blow molding section 310 and whenthe next preform 1 is carried in) required for blow molding by a blowmolding machine is approximately 3.6 to 4.0 seconds.

[0246] In the case of this preferred embodiment, wherein the preforms 1are cooled by the injection core mold 50 even after being released fromthe injection cavity mold 42 and then blow molded thereafter, the timerequired for molding a preform for this kind of general-purposemedium-sized container is shortened to about ¾ of that of a conventionalinjecting stretch blow molding machine, and an injection molding cycletime of approximately 10 to 15 seconds is sufficient.

[0247] Therefore, if this injection molding cycle time (approx. 10 to 15seconds) is T1 and the blow molding cycle time (3.6 to 4.0 seconds) isT2, the ratio T1:T2 is about 3:1, and it is established that in order toefficiently mold general-purpose medium-sized containers thesimultaneous molding numbers N and n should ideally be set in accordancewith this ratio. When a large container is to be molded from a thickerpreform an injection molding cycle time of 16 seconds or more issuitable and the ratio N:n can be set to around 4:1. When a smallcontainer is to be molded from a thin preform the injection moldingcycle time is shortened and consequently the ratio N:n can be set to forexample 4:2.

[0248] Thus, if N/n is set to 3, the injection molding cycle and theblow molding cycle will be suitable for molding medium-sized containers,for which the market demand is the greatest, and a blow molding machinewith little waste in the molding cycles can be realized.

[0249] Intermediate Preform Discharge Mechanism

[0250] In this preferred embodiment, as shown in FIG. 2 and FIG. 3, apreform dropout opening is provided in the part of the machine bed 8where the transfer station 200 is disposed. This preform dropout opening8 a is continuous with a chute 8 b formed inside the machine bed 8, andthis chute 8 b leads to a preform discharge opening 8 c formed in theside of the machine bed 8.

[0251] With this type of hot parison blow molding machine there arevarious situations wherein it is desirable that the transfer to the blowmolding station 300 of the preforms 1 being molded in the preformmolding station 10 be stopped. For example, when the whole blow moldingmachine is started up, until the preform 1 injection moldingcharacteristics stabilize it is preferable that the imperfect preforms 1being produced at this stage not be supplied to the blow molding station300. Also, when for some reason trouble has arisen in the blow moldingstation 300 it is preferable that only the operation of the blow moldingstation 300 be stopped and that the operation of the preform moldingstation 10 not be stopped so that preforms 1 continue to be molded. Thisis because there are various heating parts in the preform moldingstation 10 and consequently once the preform molding station 10 is shutdown a considerable amount of time is required to start it up again.

[0252] In this preferred embodiment, when such a situation arises, thepreforms 1 continuing to be injection molded in the preform moldingstation 10 are discharged to the side of the machine bed 8 through theabove-mentioned preform dropout opening 8 a, the chute 8 b and thedischarge opening 8 c instead of being transferred to the blow moldingstation 300 by the transfer station 200. This preform 1 dischargingoperation can for example be carried out by the pair of neck holdingmembers 234 of the inverting and handing over mechanism 230 taking holdof the preforms 1 as usual but then, without inverting them through180°, moving the preforms 1 for example horizontally to a predeterminedposition above the preform dropout opening 8 a in the machine bed 8 andthen simply releasing the preforms 1.

[0253] This preferred embodiment, as sequence control modes, has abottle molding operating mode wherein the preforms 1 are transferred tothe blow molding station 300 and blow molding of the bottles 6 isperformed, and a preform molding operating mode wherein the preforms 1are not transferred to the blow molding station 300. It is possible tochange over from the normal bottle molding operating mold for exampleautomatically when an abnormality is detected by a sensor or the like orby an operator flicking a manual switch. When the apparatus is switchedover to the preform molding operating mode the operation of the transferstation 200 changes over to the operation of carrying the preforms 1 tothe preform dropout opening 8 a as described above, and no furtherpreforms 1 are transferred to the blow molding station 300.

[0254] This invention is not limited to the preferred embodimentdescribed above, and various modifications can be made within the scopeof the invention.

[0255] In the preferred embodiment described above, the rotary disc 30carried both the injection core mold 50 and the neck cavity mold 60, butfor example in cases such as when the shape of the neck portion 2 doesnot form an undercut with respect to the mold-release direction it isnot always necessary to use the neck cavity mold 60. When the neckcavity mold 60 is not used, after the preforms 1 are released from theinjection cavity mold 42 in the injection molding section 14, thepreforms 1 can be carried to the preform ejecting section 16 by theinjection core mold 50 alone. Because the preforms 1 contract around thecore pins 52 of the injection core mold 50 as they cool they can besmoothly released from the injection cavity mold 42, and the preform 1can be carried by the injection core mold 50 even without there beingany undercut at the neck portion 2.

[0256] In the preform ejecting section 16, to remove the injection coremold 50 from the preforms 1, for example the core pins 52 of theinjection core mold 50 can be provided with a function enabling them tointroduce air for ejection into the preforms 1. When this is done, inthe preform ejecting section 16, by blowing air from the core pins 52into the preforms 1 after they are cooled by the injection core mold 50,the preforms 1 can be caused to drop downward by this air pressure.

What is claimed is:
 1. An injection stretch blow molding apparatus,comprising: a preform molding station for injection molding preforms; ablow molding station for stretch blow molding the preforms intocontainers; and a transfer station for transferring the preforms fromthe preform molding station to the blow molding station, wherein thepreform molding station comprises an injection molding section forsimultaneously injection molding a first number N (N>2) of the preformsat a first pitch, wherein the blow molding station comprises: acirculatory carrier for intermittently circulatorily carrying thepreforms along a carrying path at a second pitch larger than the firstpitch, the preforms being transferred from the preform molding stationthrough the transfer station; a heating section for heating the preformsbeing transferred along the carrying path; and a blow molding sectionfor simultaneously blow molding n (1≦n<N) of the containers from asecond number n of the preforms, and wherein the transfer stationcomprises: a receiving mechanism for receiving the preforms from thepreform molding station; an inverting mechanism for inverting thepreforms; and a pitch changing mechanism for changing an array pitch ofthe preforms from the first pitch to the second pitch.
 2. The injectionstretch blow molding apparatus as defined in claim 1 , wherein eachpreform has a neck and the pitch changing mechanism includes two necksupporting mechanisms each of which supports the neck of the preform. 3.An injection stretch blow molding apparatus, comprising: a preformmolding station for injection molding preforms; a blow molding stationfor stretch blow molding the preforms into bottles; a transfer stationfor transferring the preforms from the preform molding station to theblow molding station; and a machine bed on which the preform molding,blow molding and transfer stations are provided, wherein the blowmolding station comprises: a receiving section for receiving at leastone preform from the preform molding station through the transferstation; a circulatory carrier for intermittently circulatorily carryingthe preforms along a carrying path, the preforms being received from thereceiving section; a heating section for heating the preforms carriedalong the carrying path; a blow molding section for blow molding the atleast one preform carried along the carrying path into the at least onebottle; and a bottle ejecting section for ejecting the at least onebottle outside the apparatus, and wherein the blow molding section isprovided at an end side of the machine bed opposite the receivingsection.
 4. The injection stretch blow molding apparatus as defined inclaim 3 , wherein the machine bed is substantially rectangular, andwherein the preform molding, transfer and blow molding stations arealigned on the machine bed.
 5. An injection stretch blow moldingapparatus comprising: an injection molding station for injection moldingat least one preform in an upright state with open neck portion of theat least one preform facing upward; a blow molding station for blowmolding the at least one preform into at least one container in aninverted state; and a transfer station which turns the at least onepreform upside-down and transfers the at least one preform to the blowmolding station in an inverted state; and wherein the transfer stationcomprises: a holding mechanism for holding the at least one preform; andan inverting drive device for rotating the holding mechanism about ahorizontal axis, thereby the at least one preform is turned from theupright state to the inverted state.
 6. The injection stretch blowmolding apparatus as defined in claim 5 , wherein: the injection moldingstation injection molds at least two preforms at a first pitch; and theblow molding station comprises a circulatory carrier for intermittentlycirculatorily carrying the at least two preforms along a carrying pathat a second pitch larger than the first pitch; and wherein the transferstation further comprises: a pitch changing mechanism for changing anarray pitch of the at least two preforms from the first pitch to thesecond pitch.